Prevalence of aster yellows (AY) and elm yellows (EY) group phytoplasmas in symptomatic grapevines in three areas of northern Italy

Flavescence doree (FD) and others important grapevine yellows (GY) diseases are known to occur in northern Italy. In this communication we report the results of an extended survey of naturally yellows diseased grapevines growing in three provinces of northern Italy, Vicenza, Brescia and Pavia. The plants were sampled at the end of June and the beginning of August. Direct PCR assay using group-specific primers for universal phytoplasma 16S rDNA amplification or for amplification of 16S rDNA from 16SrI (aster yellows and related phytoplasmas), 16SrIII (X-disease and related phytoplasmas) and 16SrV (elm yellows and related phytoplasmas) phytoplasma groups, and RFLP analysis of amplified DNA, were conducted. Phytoplasmas belonging to group 16SrV were detected only in grapevines in the Vicenza province; whereas, phytoplasmas belonging to group 16SrI subgoup G were found in grapevines in all three provinces

Grapevine flavescence doree and other yellows of grapes. Flavescenza dorata e altri giallumi della vite

After c. 15 years from its first appearance in Veneto, Italy, grapevine flavescence doree (phytoplasmas) now affects most of the viticultural area of that region. The features distinguishing flavescence doree from other yellows diseases are described. The incidence of flavescence doree in Vicenza is summarized from observations and experiments conducted in that province and from information in the literature, with particular reference to symptomatology, epidemiology and control. Control strategies are recommended. The importance of protecting healthy nursery plants from the vector, the cicadellid Scaphoideus titanus, by nets or repeated insecticide treatments is stressed

Evidence that the Closteroviruses GLRV-1 and GLRV-3 are causal agents of grapevine Leafroll disease

Young grapevine plants originated from virus-free clones of the cultivars Barbera and Pinot noir and from the hybrid LN-33 were inoculated by green grafting with grape sources infected only with grapevine leafroll-associated closterovirus 1 (GLRaV-1) or GLRaV-3. Green grafting was successful in most cases, and both GLRaV-1 and GLRaV-3 were capable of causing leafroll symptoms in inoculated vines. It is concluded that the 2 viruses found in northern Italy can be considered as causal agents of the grapevine leafroll disease and can be named "grapevine leafroll virus 1" and "grapevine leafroll virus 3", respectively